1. Technical Field
Embodiments of the subject matter disclosed herein relate generally to apparatuses, methods and systems and, more particularly, to devices, processes, mechanisms and techniques for detecting and measuring cracks in metallurgical vessels.
2. Description of Related Art
Metallic vessels or containers of various sizes and shapes designed to hold molten metals are widely used in many industrial applications. Example of these applications include, but are not limited to, gasification processes in chemical and power production, Electric-Arc Furnaces (EAF), Basic Oxygen Furnaces (BOF), ladles, blast furnaces, degassers, and Argon-Oxygen-Decarburization (AOD) furnaces in steel manufacturing. As known in the art, these containers are normally lined with refractory material installed in brick form or cast in monolithic blocks in order to protect the metallic part of the vessel from the high-temperature contents placed therein; however, due to normal wear and tear of the refractory material through the combined effects of oxidation, corrosion, and mechanical abrasion, some portion of the refractory surface in contact with the molten metal is lost during processing, thus requiring frequent inspection so as to assure extended use by performing early localized repair in order to avoid possible catastrophic failures and unnecessary or premature refurbishment of the entire vessel's refractory lining.
FIG. 1 shows a conventional metallurgical container 2 having a shell 4, an internal layer of refractory material 6, and an opening 8. The dashed line 7 in FIG. 1 illustrates the original layer of refractory material before the container was placed in use. The difference between lines 7 and 6 is what existing systems are configured to detect in order for an operator to decide when to take the container out of service for repair. A specific wear pattern that creates potential hazards is cracks in the refractory material 6. Cracks allow molten metal to flow closer to the outer steel shell of the vessel 4, thereby creating increased probability of melting the shell 4. Melting the shell 4 is commonly referred to as “breakout” and is considerate by some to be a catastrophic failure mode that can cause significant damage and/or injury.
Initially characterization of the refractory thickness in these metallurgical containers was done visually by experienced operators. Given the hostile environment and the long downtime required that approach was quickly abandoned with the advent of automated systems. As understood by those of ordinary skill in the art, conventional automated processes are known to measure the localized thickness, i.e., the localized distance between the internal layer of refractory material 6 and the containers shell 4. A widely used conventional method for measuring the remaining lining thickness of metallurgical vessels is laser scanning.
FIG. 2 shows a conventional laser scanning refractory lining thickness measurement system 10 comprising a mobile cart 12, a laser scanning system 16 mounted thereon, and associated hardware and software located in the mobile cart 12. One of the goals of the laser scanning system 10 when used in metallurgical vessels is to accurately measure the lining thickness to allow a vessel to remain in service for as long as possible and to indicate areas requiring maintenance. A typical laser scanning system 14 includes a laser, a scanner, optics, a photodetector, and receiver electronics (not shown).
Such lasers are configured to fire rapid pulses of laser light at a target surface, some at up to 500,000 pulses per second. A sensor on the instrument measures the amount of time it takes for each pulse to bounce back from the target surface to the scanner through a given field of view 16 in FIG. 2. Light moves at a constant and known speed so the laser scanning system 14 can calculate the distance between itself and the target with high accuracy. By repeating this in quick succession the instrument builds up a complex ‘map’ of the surface it is measuring. By calculating and/or comparing changes between measured range maps of the internal surfaces of the refractory material 6 with reference measurement of the same surfaces, changes are detected and evaluated for possible changes that may result in a failure of the shell 4. Single measurements can be made in 20 to 30 seconds. An entire map of the furnace interior consisting of, for example, 4 to 6 measurements and more than 2,000,000 data points can be completed in a short time period (e.g., less than 10 minutes). Laser scanning produces a large collection of data points sometimes referred to as a cloud of data points.
However, despite the above-summarized progress in characterizing the wear on the refractory material 6 of the metallurgical container 2, to date no devices, processes, and/or methods exist that are capable of detecting and measuring a crack in the refractory surface 6. Therefore, based at least on the above-noted challenges with conventional laser scanning devices to characterize the integrity of vessels and to measure surface profiles thereof, it would be advantageous to have devices, methods, and systems capable of detecting, measuring, and/or characterizing cracks in the refractory material 6. Such a characterization would include the ability to quantify a maximum crack depth, location, orientation, length, average width, and maximum width. This information could then be presented to a knowledgeable user who would be able to determine the severity of a crack and evaluate if the metallurgical vessel requires maintenance or re-lining even before refractory scanning results in refractory wear below minimum safety levels.